So run the left and right turn signal to the same "Stop Light"? Wouldn't neither blink? Seems they would be shorted together? Mine are not wired individually except inside the trailer. Not at the 4 pin connector.
I may have condensed it too much.
If we are looking at my trailer, and the 1157 bulbs that are in the Marine Stop/Run/Signal light assembly.
The Stop Lamp/Turn filament is the biggest one, and the brightest.
that will now be the Turn Signal only.
The Left turn wire on the bike, goes to the Left trailer Stop Lamp filament.
The Right turn wire on the bike, goes to the Right trailer Stop Lamp filament.
The standard, "running light" is still just that, the smaller filament is just for Running Lights and all of the lights are normally run from just that one wire.
The bike's brake light wire which is BLUE is extended to the trailer runs to the 3 extra lights that I bought purposely to be used as the STOP lights.
This Blue Wire is not included in most trailer wiring hookups, but it should be.
If I understand you correctly, your trailer is using the same exact light assembly as the standard GL1800 Saddle Bags are?
if so, you only need to go from wire color on the bike, to the same exact wire color on the trailer's light assembly.
There should be a Blue wire in the trailer's light assembly and it should be going to the Stop Lamps.